Patterning method for OLEDs

ABSTRACT

Methods of fabricating a device having laterally patterned first and second sub-devices, such as subpixels of an OLED, are provided. Exemplary methods may include depositing via organic vapor jet printing (OVJP) a first organic layer of the first sub-device and a first organic layer of the second sub-device. The first organic layer of the first sub-device and the first organic layer of the second sub-device are both the same type of layer, but have different thicknesses. The type of layer is selected from an ETL, an HTL, an HIL, a spacer and a capping layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/863,293, filed Sep. 23, 2015, which is a divisional of U.S.application Ser. No. 14/581,594, filed Dec. 23, 2014, which is adivisional of U.S. application Ser. No. 13/600,444, filed Aug. 31, 2012,the disclosure of each of which is incorporated by reference in itsentirety.

FIELD OF THE INVENTION

The present invention relates to methods of producing organic lightemitting devices, and more specifically to manufacturing processes forproviding layer thicknesses for microcavity optimization without the useof a shadow mask.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the structure of Formula I:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule.” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY OF THE INVENTION

This present invention is related to the field of OLED manufacturing. Inparticular, the invention provides methods for forming a pattern ofdifferent layer thicknesses, e.g. for microcavity optimization, withoutthe use of a shadow mask. As discussed further below, differentthicknesses of organic layers may be achieved, for example, bydepositing organic layers of similar functional type using organic vaporjet printing (OVJP), or similar processes.

As used herein, OVJP should be understood as a deposition process thattypically includes the steps of 1) heating an organic material in acrucible, causing it to evaporate, 2) passing an inert carrier gas suchas nitrogen over the hot organic material, thereby entraining organicvapor within the carrier gas, and 3) flowing the carrier gas with theorganic vapor down a tube, where it is ejected onto a substrate via anozzle to form a thin, laterally patterned organic film. In embodiments,the substrate may be cooled to assist with the deposition of the film.

Embodiments of OVJP generally involve a “jet” of gas ejected from thenozzle, as distinct from other techniques, such as OVPD (organic vaporphase deposition), where a carrier gas may be used, but there is no“jet.” A “jet” occurs when the flow velocity through the nozzle issufficiently large to result in a significantly anisotropic velocitydistribution relative to the isotropic velocity distribution of themolecules in a stagnant gas. One way of defining when a jet occurs iswhen the flow velocity of the carrier gas is at least 10% of the thermalvelocity of the carrier gas molecules.

One unique aspect of OVJP is that the organic species may be acceleratedby the flow of a much lighter carrier gas to hyperthermal velocities.This can lead to denser and more ordered thin films, which potentiallybroadens the processing window for ultra-rapid growth of high qualitythin films for device applications. This acceleration may also allow theinstantaneous local deposition rate of OVJP to exceed that of thealternative broad-area deposition methods, resulting in an advantage inthe rapid printing of large-scale electronics.

Because OVJP does not use liquid solvents, it may allow for greaterlatitude in the choice of substrate material and shape than otherprocesses such as ink-jet printing, thereby permitting a wider varietyof organic semiconductors and structures to be deposited. The moleculesused for organic devices typically have vapor pressures of up to severalmillibar, allowing high practical deposition rates. OVJP is preferablyused to deposit small molecule organic materials because they generallyhave sufficient vapor pressure at reasonable temperatures to allow for ahigh deposition rate. However, OVJP may have applications to othermaterials, such as polymers.

According to first aspects of the invention, a method of fabricating adevice having at least laterally patterned first and second sub-devicesis provided. The method may include depositing a first organic layer ofthe first sub-device and a first organic layer of the second sub-device.In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may have differentthicknesses. As used herein, a “different thickness” is intended tosignify a difference that is intended, and is typically greater than themere processing imperfections in deposited layers that are otherwiseintended to be the same thickness. In embodiments, the first organiclayer of the first sub-device and the first organic layer of the secondsub-device may be deposited with different thicknesses without the useof a shadow mask, for example, the first organic layer of the firstsub-device and/or the first organic layer of the second sub-device maybe deposited via OVJP.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may both be the same typeof layer. For example, both layers may be an electron transport layer(ETL), a hole transport layer (HTL), a hole injection layer (HIL), aspacer or a capping layer.

Embodiments may also include steps of providing first and secondelectrodes to each of the first and second sub-devices. At least one ofthe first and second electrodes of the first and second sub-devices maytypically be individually addressable, although one or both may becommon electrodes.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may have the same materialcomposition.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may have different materialcompositions.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may be deposited at thesame time.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may be deposited at thesame time and have the same material composition.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may be deposited atdifferent times.

In embodiments, the first organic layer of the first nub-device and thefirst organic layer of the second sub-device may be deposited atdifferent times and have the same material composition.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may be deposited atdifferent times and have different material compositions.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may be disposed withinoptical cavities.

In embodiments, the first and second sub-devices may be OLEDs.

In embodiments, the first and second sub-devices may each emit adifferent color of light.

In embodiments, the device may further include a third sub-device, andthe first, second and third sub-device's may each emit a different colorof light. For example, the first, second and third devices may each emita different color selected from red, green and blue.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may have a thicknessdifference greater than, for example, approximately 5 Å approximately 10Å, or approximately 20 Å.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device have a thickness differencein a range of approximately 10 Å-400 Å, or in a range of approximately10 Å-1000 Å.

In embodiments, the lateral separation between the first and secondsub-devices is at most approximately 1.0 mm.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may both be HTLs, and ahole transport property of the first organic layer of the firstsub-device may be different from a hole transport property of the firstorganic layer of the second sub-device.

In embodiments, the first organic layer of the first sub-device and thefirst organic layer of the second sub-device may both be HTLs, and atriplet state energy of the first organic layer of the first sub-deviceis within 0.3 eV of a triplet state energy of the first organic layer ofthe second sub-device.

In embodiments, the device may be a consumer device.

In embodiments, the device may be incorporated into an optoelectronicdevice, such as in a vehicle, a computer, a television, a printer, alarge area wall, a theater or stadium screen, a billboard, or a sign.

As used herein, “emitters,” “emitting layers,” and “emissive dopants”should be understood as encompassing those structures and materials thatare intended to emit in the actual device(s). That is, although somestructures and/or materials may exhibit incidental and/or unintendedemissions at a certain low-level (e.g. less than 5% of photons emitted),such emissions are not considered to fall within the claimed “emitters,”“emitting layers,” or “emissive dopants” unless specifically indicated.To the extent that emissive dopants are claimed, they should also not beconsidered as including, or corresponding to, the host material, even inthe event that the host itself is emissive or exhibits incidentalemissions. That is, an “emissive dopant” is generally used to identify aminority component that is intended to emit in the device (e.g. greaterthan 5% of the photons emitted). Emission from the hole and/or electrontransport layers are generally not considered as filing within thedefinition either.

As used herein, a “spacer” layer should generally be understood asincluding layers used to control the cavity length in a device. Thesemay be, for example, a substantially transparent layer that increasesthe separation of an emissive layer from one of the surfaces of amicrocavity in which the emissive layer sits. In embodiments, the spacerlayer may be an extra thickness added to the HTL or ETL. The spacerlayer may be an unpatterned layer, or it may be patterned. The spacerlayer may be deposited by the same, or different, methods than theadjacent emissive layer.

As used herein, at “capping” may refer to a layer of material that isdeposited over the top electrode of an OLED (which is typically thecathode). The capping layer is typically used to enhance the amount oflight outcoupled from the OLED. The layer may be made of any suitablematerial (such as Alq₃), and is preferably transparent,semi-transparent, or translucent. The term “total capping layer” mayrefer to the combination of all of the capping layers disposed over (andoptically coupled to) an OLED. For instance, if a first and secondcapping layer are disposed over an OLED such that they are all opticallycoupled, the total capping layer of the OLED) is the combination of thefirst and second capping layers. The “total optical thickness” is theoptical thickness of the total capping layer. The capping layer may bedeposited by the same, or different, methods than the adjacent layer.

The materials used for spacer and/or capping layers may be chosen basedon various intended effects, such as to control microcavity emission, toprovide an optical effect, or to prevent contamination between multipleemissive, or other, layers. For example, a transparent layer can beincorporated in or on each color OLED and designed to be the correctthickness to optimize the microcavity for that particular color.According to aspects of the invention, spacing and/or capping layers maybe manufactured with organic materials using OVJP deposition. However,the invention is not limited to such embodiments, and exemplary devicesmay include other inorganic materials in non-OVJP deposited layers, forexample, capping layers with materials such as LiF.

According to further aspects of the invention, devices and sub-devicessuch as those described herein may be provided in, for example, amulti-color pixel, or a white-light application. Exemplary devices maybe included in a system that includes only one type of emitter, e.g. awhite light emitter in a cool white light system, or they may beincluded with other color emitters, each of which may representdifferent color pixels of a color display, e.g. an RGB display.

As used herein, “red” means having a peak wavelength in the visiblespectrum of 600-700 nm, “green” means having a peak wavelength in thevisible spectrum of 500-600 nm. Other color emitters are alsocontemplated as within the scope of the invention.

As used herein, “light blue” and “dark blue” may both generally refer tohaving a peak wavelength of between 400 to 500 nanometers. Inembodiments, a peak wavelength of between 400 to 470 nanometers mayrefer to “deep blue” and a peak wavelength of between 460 to 500 mayrefer to “light blue.” However “light blue” and “deep blue” may also beused in the relative sense when comparing emissive dopants included inthe same device. For example, a “light blue dopant” may be understood asthe dopant having a peak wavelength that is (1) between 400 to 500nanometers, and (2) greater than (e.g. at least 4 nm greater than) thepeak wavelength of another dopant having a peak wavelength of between400 to 500 (i.e. a “dark blue dopant”).

Any first, second or third sub-devices described herein each have atleast one emissive layer that includes a phosphorescent or fluorescentorganic material that emits light when an appropriate voltage is appliedacross the device.

Any first, second or third sub-devices described herein may have thesame surface area, or may have different surface areas.

Further advantages of the present subject matter will become apparent tothose of ordinary skill in the art upon reading and understanding thefollowing detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the detailed description serve to explain the principlesof the invention. No attempt is made to show structural details of theinvention in more detail than may be necessary for a fundamentalunderstanding of the invention and various ways in which it may bepracticed. In the drawings:

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a schematic cross sections of a device structure withdifferent thicknesses of HTL.

FIG. 4 shows a schematic cross sections of a device structure withdifferent thicknesses of ETL.

FIG. 5 shows a schematic cross sections of a device structure withdifferent thicknesses of ETL and HTL.

FIG. 6 shows a schematic cross sections of a device structure withdifferent thicknesses of a transparent capping layer.

FIG. 7 shows a schematic cross sections of a device structure withdifferent thicknesses of a transparent layer configured to optimize theoutcoupling of different component colors of a white light emitter.

FIG. 8 shows a schematic cross sections of a top-emitting devicestructure with different thicknesses of an HTL and optional color filterlayers over the sub-pixels.

FIG. 9 shows a schematic cross sections of a bottom-emitting devicestructure with different thicknesses of an HTL and optional color filterlayers under the transparent substrate.

FIG. 10 shows a schematic cross sections of a top-emitting devicestructure with different thicknesses of an ETL and optional color fi terlayers over the sub-pixels.

FIG. 11 shows a schematic cross sections of a bottom-emitting devicestructure with different thicknesses of an ETL and optional color filterlayers under the transparent substrate.

FIG. 12 shows a schematic cross sections of a top-emitting devicestructure with different thicknesses of an HTL and ETL and optionalcolor filter layers over the sub-pixels.

FIG. 13 shows a schematic cross sections of a bottom-emitting devicestructure with different thicknesses of an HTL and ETL and optionalcolor filter layers under the transparent substrate.

FIG. 14 shows a schematic cross sections of a top-emitting devicestructure with different thicknesses of a transparent layer and optionalcolor filter layers over the sub-pixels.

FIG. 15 shows a schematic cross sections of a device with differentthicknesses of a transparent layer configured to optimize theoutcoupling of different component colors of a white light emitter, andoptional color filter layers over the sub-pixels.

FIG. 16 shows a schematic cross sections of a device with a white lightEML different thicknesses of an HTL, and optional color filter layersover the sub-pixels.

FIG. 17 shows a schematic cross sections of a device with a white lightEML, different thicknesses of an HTL and a transparent layer, andoptional color filter layers over the sub-pixels.

FIG. 18 shows a schematic cross sections of a top-emitting devicestructure with a white light EML, different thicknesses of an ETL, andoptional color filter layers over the sub-pixels.

FIG. 19 shows a schematic cross sections of a top-emitting devicestructure with a white light EML, different thicknesses of an ETL, andtransparent layer, and optional color filter layers over the sub-pixels.

FIG. 20 shows a schematic cross sections of a bottom-emitting devicestructure with a white light EML, different thicknesses of an HTL, andoptional color filter layers under the substrate.

FIG. 21 shows a schematic cross sections of a bottom-emitting devicestructure with a white light EML, different thicknesses of an ETL, andoptional color filter layers under the substrate.

FIG. 22 shows a schematic cross sections of a top-emitting devicestructure with a blue light EML, different thicknesses of a transparentlayer, and optional color filter layers and color conversion materialover the sub-pixels.

FIG. 23 depicts an exemplary full-color display according to aspects ofthe invention.

FIG. 24 depicts an exemplary lighting panel according to aspects of theinvention.

FIG. 25 shows spectral output results from an embodiment where the HTLthickness is adjusted using OVJP deposition to optimize the color purityof a green OLED.

DETAILED DESCRIPTION

It is understood that the invention is not limited to the particularmethodology protocols, and reagents, etc., described herein, as thesemay vary as the skilled artisan will recognize. It is also to beunderstood that the terminology used herein is used for the purpose ofdescribing particular embodiments only, and is not intended to limit thescope of the invention. It also is be noted that as used herein and inthe appended claims, the singular forms “a,” “an,” and “the” include theplural reference unless the context clearly dictates otherwise. Thus,for example, a reference to “a pixel” is a reference to one or morepixels and equivalents thereof known to those skilled in the art.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meanings as commonly understood by one of ordinary skillin the art to which the invention pertains. The embodiments of theinvention and the various features and advantageous details thereof areexplained more fully with reference to the non-limiting embodiments andexamples that are described and/or illustrated in the accompanyingdrawings and detailed in the following description. It should be notedthat the features illustrated in the drawings are not necessarily drawnto scale, and features of one embodiment may be employed with otherembodiments as the skilled artisan would recognize, even if notexplicitly stated herein. Descriptions of well-known components andprocessing techniques may be omitted so as to not unnecessarily obscurethe embodiments of the invention. The examples used herein are intendedmerely to facilitate an understanding of ways in which the invention maybe practiced and to further enable those of skill in the art to practicethe embodiments of the invention. Accordingly, the examples andembodiments herein should not be construed as limiting the scope of theinvention, which is defined solely by the appended claims and applicablelaw. Moreover, it is noted that like reference numerals referencesimilar parts throughout the several views of the drawings.

Generally an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-1”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett, vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporated byreference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, and a cathode 160. Cathode 160 is acompound cathode having a first conductive layer 162 and a secondconductive layer 164. Device 100 may be fabricated by depositing thelayers described, in order. The properties and functions of thesevarious layers, as well as example materials, are described in moredetail in U.S. Pat. No. 7,279,704 at cols. 6-10, which are incorporatedby reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F.sub.4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100).

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove outcoupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Although aspects of the invention specifically relate to forming apattern of different layer thicknesses using OVJP, it should beunderstood that, unless otherwise specified, any of the layers of thevarious embodiments may be deposited by any suitable method. For theorganic layers, preferred methods include thermal evaporation, ink-jet,such as described in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by OVJP, such as described in U.S. Pat. Nos. 7,431,968 and7,744,957, which are incorporated by reference in their entireties.Other suitable deposition methods include spin coating and othersolution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink-jet and OVJD. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processability than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the invention maybe incorporated into a wide variety of consumer products, includinglights for interior or exterior illumination and/or signaling, laserprinters, flat panel displays, computer monitors, televisions,billboards, heads up displays, fully transparent displays, flexibledisplays, telephones, cell phones, personal digital assistants (PDAs),laptop computers, digital cameras, camcorders, viewfinders,micro-displays, vehicles, a large area wall, theater or stadium screen,or a sign. Various control mechanisms may be used to control devicesfabricated in accordance with the present invention, including passivematrix and active matrix. Many of the devices are intended for use in atemperature range comfortable to humans, such as 18 degrees C. to 30degrees C., and more preferably at room temperature (20-25 degrees C.).

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

The terms halo, halogen, alkyl, cycloalkyl, alkenyl, alkynyl, arylkyl,heterocyclic group, aryl, aromatic group, and heteroaryl are known tothe art, and are defined in U.S. Pat. No. 7,279,704 at cols. 31-32,which are incorporated herein by reference.

As discussed previously, a typical OLED device comprises anode, organiclayers and cathode. Either the anode or cathode or both is typically aTCO or thin metal. The organic emissive layer therefore sits in a weakmicrocavity which influences the spectral content and efficiency of theemitted light. This effect is described, for example, in P. E. Burrowset al., Appl. Phys. Lett. 73, 435 (1998) or V. Bulovic, V. B. Khalfin etal., Phys. Rev. B. 58, 3730 (1998) and references therein.

Because of the microcavity effect, it is sometimes desirable to usedifferent organic stack thicknesses to optimize different colors emittedfrom a laterally-patterned OLED panel, or to use different transparentlayer thicknesses to preferentially select different colors from abroad-band or white emission spectrum. For example, a display mightinclude separately patterned R, G and B sub-pixels and each of thesepixels might have a different HTL thickness in order to optimize theefficiency and spectral purity of each color. Alternatively, an OLEDlamp might be comprised of laterally-patterned R, G and B stripes, eachof which might include an emitter layer located in microcavities ofdiffering optical path lengths.

Such microcavity structures can be tuned by adjusting the thickness ofthe HTL, ETL, EML or some combination of multiple layers. Alternatively,a transparent layer can be incorporated in or on each color OLED anddesigned to be the correct thickness to optimize the microcavity forthat particular color.

There is, therefore, a need for a manufacturable method to depositlaterally-patterned OLEDs on a substrate with not only EML layers ofdifferent composition (e.g. R, G, B emitters) but also charge transportor inert layers of different thickness. The term “manufacturable” ismeant to imply a low-cost and high throughput process.

One problem in particular involves limiting the overspray of one lightemitting material onto the HTL of adjacent pixels of different color.This problem is particularly important to solve because even a verysmall amount of emitter layer contamination (<<1 monolayer) cansignificantly affect the performance of an OLED. We have found thatcareful design of the nozzle shape(s) and arrangement can minimizeoverspray. See, e.g., co-pending U.S. patent application Ser. No.13/595,160, the contents of which are hereby incorporated by reference.

However, the inventors have found that it is possible to control thethickness of laterally-patterned ETL, HTL or other organic spacer,capping or other layers using OVJP with far less concern for smallamounts of overspray, and therefore fewer constraints on the nozzledesign. The inventors have demonstrated this, for example, by using anOVJP-deposited HTL to optimize the microcavity length of a green OLED.

The inventors have previously disclosed that an EML may effectively bepatterned by OVJP. For example, the inventors have determined a workablecombination of OVJP precision and tolerance for overspray that makes thepatterning of even EML layers, which are extremely sensitive tocross-contamination, possible with a simple nozzle design. In thisregard, it is also noted that other known patterning techniques, such asvacuum thermal evaporation (VTE), ink-jet printing (IJP), or nozzleprinting, are impractical for patterning of EML of organic emittingpixels over large areas because of the non-scalability of shadow masks,and the impossibility of depositing pixels with a combination of goodefficiency and good lifetime using IJP. The inventors have furtherdiscovered that the patterning of the HTL or ETL is easier to accomplishusing OVJP because a small (˜few monolayer) overspray of the HTL or ETLonto an adjacent patterned electrode will not substantially affect theperformance of the device.

Accordingly, as discussed below with respect to certain exemplaryembodiments, aspects of the invention may include using, for example,OVJP to deposit at least one layer of an OLED so that it is laterallypatterned with different thicknesses over different parts of thesubstrate. The OVJP-patterned layer might be the HTL, the ETL, or both.Furthermore the OVJP-patterned layer might be an additional layer notbetween the OLED electrodes, e.g. a layer on top of the transparentcathode of a top-emitting device or underneath the transparent anode ofa bottom-emitting device. Exemplary devices may also be described in thecontext of devices including three sub-devices (or subpixels). However,it should be understood that the techniques are equally applicable todevices including only two sub devices, or more than three sub devices.

In the following embodiments, the substrate includes a first electrode.The substrate may be glass, plastic or metal foil and the firstelectrode may be a metal or a TCO. The substrate may include a firstelectrode that is patterned so as to form sub-pixels. For clarity, oneor more similarly functioning layers may be referred to by commonnumbers throughout the various embodiments, e.g. a “first electrode”310, an HTL 320, an EML 330, an ETL 340, and a “second electrode” 350.However, this is in no way intended to imply that such commonly-numberedlayers are in all respects identical, as will be apparent.

A first embodiment is described with reference to FIG. 3: Asubstrate/first electrode 310 may be loaded into an OVJP chamber. An HTL320 (and/or an HIL) may be deposited using OVJP so that a firstthickness of HTL and/or HIL is deposited on a first set of sub-pixels410. A second thickness of HIL and/or HTL may be deposited on a secondset of sub-pixels 420. A third thickness of HIL and/or HTL may bedeposited on a third set of sub-pixels 430. In this example, and theothers that follow, the “first thickness,” “second thickness” and “thirdthickness” are to be understood as different thicknesses, i.e. includinga difference that is intended, and is typically greater than the mereprocessing imperfections in deposited layers that are otherwise intendedto be the same thickness. For example, the first thickness, secondthickness and third thickness may include differences greater thanapproximately 5 Å, approximately 10 Å, or approximately 20 Å. Thedifferent thicknesses may alternatively be in a range of, for example,10 Å-100 Å, or in a range of approximately 10 Å-1000 Å. It should benoted that, unless otherwise specified, references to HTL in thefollowing descriptions of the figures may also refer to variations inHIL, the HIL and HTL, or other transparent layer(s) involved in holetransport.

In embodiments such as shown in FIG. 3, in which the HTL includesdifferent thicknesses, (1) a hole transport property of the HTL in thefirst sub-pixel 410 may be different from a hole transport property ofthe HTL in the second sub-pixel 420 and/or the third sub-pixel 430,and/or (2) a triplet state energy of the HTL in the first sub-pixel 410may be within 0.3 eV of a triplet state energy of the HTL of the secondsub-pixel 420 and/or the third sub-pixel 430.

In embodiments, the lateral separation between each of sub-pixels 410,420 and 430, may be, for example, at most approximately 1.0 mm, or otherappropriate distance for white light OLED pixels or multi-color OLEDpixels.

In this embodiment, and various others described below, it should beunderstood that the layer including different thicknesses may bedeposited substantially at the same time (e.g. by using OVJP jets withdifferent deposition rates), or at different times, which may include,for example, drawing different lines of material at different times withdifferent rates of deposition or pass-speed, or providing additionalpasses on the “thicker” portion of the layer. The layer having differentthicknesses may include substantially similar materials, such as in somecases of HTL, HIL, ETL, spacer or capping layers, or may includedifferent materials, such as different organic emitting compounds in anEML of a multi-color OLED pixel. In this regard, it should also beunderstood that the use of the term “layer” is not necessarily meant toimply a contiguous or simultaneously formed structural element. Rather,“layers” having different thicknesses more generally refer to similar(though not necessarily identical) structural elements that typicallyshare a relative functional position in an OLED stack.

Returning to FIG. 3, an EML 330 may then be deposited. e.g. using VTEand shadow mask(s), or other techniques including OVJP. Optionally, adifferent EML may be deposited on each set of sub-pixels 410, 420, 430,such as a Red EML, a Green EML and a Blue EML. As discussed furtherherein, a blue EML may include a combination of light blue and deep blueemitters. The device may be finished conventionally using VTE, possiblyincluding deposition of an ETL 340 and a top second electrode 350.

A second embodiment is described with reference to FIG. 4: HIL and/orHTL 320 and EML 330 may all be deposited on sets of sub-pixels 410, 420,430, conventionally using VTE and (optionally) shadow masks (the shadowmask being optionally used if different thicknesses and/or compositionsare used for different sub-pixels). The substrate may be subsequentlyloaded into an OVJP chamber, and a first thickness of ETL 340 isdeposited on a first set of subpixels 410 and a second thickness of ETL340 is deposited on a second set of sub-pixels 420. A third thickness ofETL 340 may be deposited on a third set of sub-pixels 430.

A second electrode 350 may be deposited, for example, using conventionalVTE.

A third embodiment is described with reference to FIG. 5. A firstthickness of HIL and/or HTL 320 is deposited on a first set ofsub-pixels 410 and a second thickness of HIL and or HTL 320 is depositedon a second set of sub-pixels 420, e.g. using OVJP. A third thickness ofHIL and/or HTL 320 may be deposited on a third set of sub-pixels 430,e.g. by OVJP.

An EML 330 may then be deposited, e.g. OVJP, or other techniques.Optionally, a different EML may be deposited on each set of sub-pixels410, 420, 430, such as a Red EML, a Green EML and a Blue EML. Of note,the EML 330 in FIG. 5 may have the same or different thicknesses.

A first thickness of ETL 340 is deposited on the first set of sub-pixels410, and a second thickness of ETL 340 is deposited on the second set ofsub-pixels 420 also using OVJP. A third thickness of ETL 340 may bedeposited on the third set of sub-pixels 430, e.g. by OVJP. Thus, thedevice shown in FIG. 5 may have multiple layers including differentthicknesses, all deposited by similar methods, e.g. HTL 320 and ETL 340,and optionally EML 330, may each include different thicknesses.

The remainder of the device, including second electrode 350, may befinished, for example, using conventional VTE and shadow masks.

A fourth embodiment is described with reference to FIG. 6. At least twoarrays of OLEDs are deposited using, for example, conventional VTE orink jet methods. The arrays may include first sub-pixels 410 and secondsub-pixels 420, each including a first electrode 310, an HTL 320, an EML330, an ETL 340, and a second electrode 350. A third array includingthird sub-pixels 430 may also be formed.

After completion of these portions of the sub-pixels, a first thicknessof a transparent material layer 360 may be deposited on the firstsub-pixels 410 and a second thickness of transparent material layer 360may be deposited on the second sub-pixels 420. A third thickness oftransparent material layer 360 may also be deposited on the thirdsub-pixels 430.

In embodiments, each sub-pixel 410, 420 and/or 430 may comprise EML 330of the same, or different colors.

In all of the foregoing embodiments, the thickness of layers depositedby OVJP may be adjusted so as to optimize the color purity and/oroptical outcoupling efficiency of light from the first, second and/orthird sets of sub-pixels, respectively.

The different sets of sub-pixels may have different EMLs which emit atdifferent peak wavelengths, which each require a different opticalcavity length to match the desired spectral peak and optimizeoutcoupling efficiency. Alternatively, there may be a common EML acrossthe sets of sub-pixels, but it is desired to select a different peakwavelength range from each set of sub-pixels. This may be accomplishedby building a different microcavity around the EML on each set ofsub-pixels.

Many different device structures may be manufactured according to theprinciples described above, and by forming additional layers, some withdifferent thicknesses, outside of the electrodes of the device, some ofwhich are depicted in FIGS. 7-22. These devices may include firstelectrode 310, HTL 320, EML 330, ETL 340 and second electrode 350layers, which may be formed in similar manner to those embodimentspreviously discussed, unless otherwise specified.

For example, FIG. 7 shows a schematic cross section of a top-emittingmulti-color device structure with different thicknesses of a transparentcapping layer 360 configured to optimize the outcoupling of differentcomponent colors of a white light EML 330. The appropriate thicknessesof the transparent layer 360 may be conveniently formed, for example, byOVJP, without significant concern for the effect of overspray on thesecond electrode 350.

FIG. 8 shows a schematic cross section of a top-emitting devicestructure with different thicknesses of HTL 320 (such as previouslydescribed), and includes different colored EML 330 and color filterlayer 370 over the sub-pixels 410, 420, 430. Color filter layers, suchas layer 370, may be used for various reasons depending on theconfiguration of the device and the color of the EML. For example, acolor filter layer may be used to cut the long wavelength tail on a blueemitter, which can be important because, since the eye sensitivity isgreater in the green, just a small amount of tailing can significantlyreduce the color saturation.

FIG. 9 shows a schematic cross section of a bottom-emitting devicestructure with different thicknesses of HTL 320, and includes differentcolored EML 330 and color filter layer 370 under the transparentsubstrate/electrode 310.

FIG. 10 shows a schematic cross section of a top-emitting devicestructure with different thicknesses of ETL 340, and includes differentcolored EML 330 and color filter layer 370 over the sub-pixels.

FIG. 11 shows a schematic cross section of a bottom-emitting devicestructure with different thicknesses of ETL 340, and includes differentcolored EML 330 and color filter layer 370 under the transparentsubstrate.

FIG. 12 shows a schematic cross section of a top-emitting devicestructure with different thicknesses of HTL 320 and ETL 340, andincludes different colored EML 330 and color filter layer 370 over thesub-pixels.

FIG. 13 shows a schematic cross section of a bottom-emitting devicestructure with different thicknesses of HTL 320 and ETL 340, andincludes different colored EML 330 and color filter layer 370 under thetransparent substrate.

FIG. 14 shows a schematic cross section of a top-emitting devicestructure with different colored EML 330, different thicknesses of atransparent layer 360, and a color filter layer 370 over the sub-pixels.

FIG. 15 shows a schematic cross section of a top-emitting device withwhite light EML 330 and different thicknesses of a transparent layerconfigured to optimize the outcoupling of different component colors ofthe white light emitter, and color filter layer 370 over the sub-pixels.

FIG. 16 shows a schematic cross section of a top-emitting device with awhite light EML 330, different thicknesses of HTL 320, and color filterlayer 370 over the sub-pixels.

FIG. 17 shows a schematic cross section of a top-emitting device with awhite light EML 330, different thicknesses of both HTL 320 andtransparent layer 360, and a color filter layer 370 over the sub-pixels.

FIG. 18 shows a schematic cross section of a top-emitting devicestructure with a white light EML 330, different thicknesses of ETL 340,and a color filter layer 370 over the sub-pixels.

FIG. 19 shows a schematic cross section of a top-emitting devicestructure with a white light EML 330, different thicknesses of both ETL340 and transparent layer 360, and a color filter layer 370 over thesub-pixels. Transparent layer 360 may be configured to optimize theoutcoupling of different component colors of the white light emitter.

FIG. 20 shows a schematic cross section of a bottom-emitting devicestructure with a white light EML 330, different thicknesses of HTL 320,and a color filter layer 370 under the substrate.

FIG. 21 shows a schematic cross section of a bottom-emitting devicestructure with a white light EML 330, different thicknesses of ETL 340,and a color filter layer 370 under the substrate.

FIG. 22 shows a schematic cross section of a top-emitting devicestructure with a blue light EML 330, different thicknesses oftransparent spacer layer 360, and a color filter layer 370 and colorconversion material over the sub-pixels. In this example, the colorfilter/conversion layers may be used to change the subpixel color fromthat of the blue emitters. It should be understood that, in certainembodiments, the color filter layer 370 and color conversion materialneed not be on all subpixels, i.e. if one of the subpixels is configuredto emit the same color as the EML. Transparent layer 360 may beconfigured to optimize the outcoupling of different component colors ofthe blue light emitter for the respective color conversion material ineach sub-pixel.

FIG. 23 depicts an exemplary fill-color display 600 according to aspectsof the invention in which an array of sub-pixels 410, 420 and 430 may bearranged.

FIG. 24 depicts an exemplary lighting panel 700 according to aspects ofthe invention, in which lines of multi-color (or white light) OLEDs 710may be arranged.

EXPERIMENTAL RESULTS

An embodiment, of the invention was reduced to practice by growing fivegreen devices according to the following recipe.

The anode electrode is a multilayer consisting of 500 Å of indium zincoxide (IZO)/150 Å of Silver (Ag) 200 Å of IZO. The cathode consisted of10 Å of LiF followed by 1,000 Å of Al. All device examples had organicstacks consisting of, sequentially, from the IZO/Ag/IZO surface, 100 Åthick of Compound A as the hole injection layer (HIL), OVJP printed ‘x’Å Compound B (HTL), 300 Å of Compound C doped with 12 wt % of Compound Das the emissive layer (EML). The electron transporting layers (ETL)consisted of 100 Å of Compound E as the ETL1 and 350 Å of Compound F asthe ETL2. The OVJP printed HTL thickness ‘x’ was varied in steps of 350Å; i.e: 350 Å, 700 Å, 1050 Å, 1400 Å, 1750 Å in devices A through Erespectively. Thus device A has a printed HTL thickness of 350 Å, deviceB has a printed HTL thickness of 700 Å etc. All the organic and cathodelayers were deposited by high vacuum (<10⁻⁷ Torr) thermal evaporationexcept for the OVJP printed α-NPD HTL. All devices were encapsulatedwith a glass lid sealed with an epoxy resin in a nitrogen glove box (<1ppm of H₂O and O₂) immediately after fabrication, and a moisture getterwas incorporated inside the package.

The spectral results and device performances are shown in FIG. 25, andbelow in Table 1, respectively.

TABLE 1 Device A B C D E Performance HTL = HTL = HTL = HTL = HTL = @1000 nits 350 Å 700 Å 1050 Å 1400 Å 1750 Å LE (cd/A) 16 7 8 21 20 EQE %4.9 2.2 2.5 6.5 5.4 Peak Wave- 551 514 510 510 573 length (nm) FWHM (nm)122 78 50 34 67 CIE (x, y) (0.412, (0.333, (0.246, (0.179, (0.410,0.551) 0.597) 0.613) 0.677) 0.563)

An optimum thickness of HTL for spectral purity and efficiency of thegreen light is 1400 Å. In an optimized RGB device, therefore, thisthickness of HTL may be printed using OVJP on the green subpixels. Otherthicknesses may be printed on the red and blue subpixels, each optimizedfor the outcoupling of their color, respectively.

As used herein, “red” means having a peak wavelength in the visiblespectrum of 600-700 nm, “green” means having a peak wavelength in thevisible spectrum of 500-600 nm, “light blue” typically means having apeak wavelength in the visible spectrum of 460-500 nm, and “deep blue”typically means having a peak wavelength in the visible spectrum of400-470 nm. Preferred ranges include a peak wavelength in the visiblespectrum of 610-640 nm for red and 510-550 nm for green.

To add more specificity to the wavelength-based definitions, “lightblue” may be further defined, in addition to having a peak wavelength inthe visible spectrum of 460-500 nm that is at least 4 nm greater thanthat of a deep blue OLED in the same device, as preferably having a CIEx-coordinate less than 0.2 and a CIE y-coordinate less than 0.5, and“deep blue” may be further defined, in addition to having a peakwavelength in the visible spectrum of 400-470 nm, as preferably having aCIE y-coordinate less than 0.3, preferably less than 0.2, and mostpreferably less than 0.1, and the difference between the two may befurther defined such that the CIE coordinates of light emitted by thethird organic light emitting device and the CIE coordinates of lightemitted by the fourth organic light emitting device are sufficientlydifferent that the difference in the CIE x-coordinates plus thedifference in the CIE y-coordinates is at least 0.01. As defined herein,the peak wavelength is the primary characteristic that defines light anddeep blue, and the CIE coordinates are preferred.

More generally, “light blue” may mean having a peak wavelength in thevisible spectrum of 400-500 nm, and “deep blue” may mean having a peakwavelength in the visible spectrum of 400-500 nm, and at least 4 nm lessthan the peak wavelength of the light blue. In some circumstances,embodiments of the invention may be described as including “a blue EML”and “the other blue EML” to generally refer to a LB EML and a DB EML, orvice versa.

In another embodiment, “light blue” may mean having a CIE y coordinateless than 0.25, and “deep blue” may mean having a CIE y coordinate atleast 0.02 less than that of “light blue.”

In another embodiment, the definitions for light and deep blue providedherein may be combined to reach a narrower definition. For example, anyof the CIE definitions may be combined with any of the wavelengthdefinitions. The reason for the various definitions is that wavelengthsand CIE coordinates have different strengths and weaknesses when itcomes to measuring color. For example, lower wavelengths normallycorrespond to deeper blue. But a very narrow spectrum having a peak at472 may be considered “deep blue” when compared to another spectrumhaving a peak at 471 nm, but a significant tail in the spectrum athigher wavelengths. This scenario is best described using CIEcoordinates. It is expected that, in view of available materials forOLEDs, that the wavelength-based definitions are well-suited fir mostsituations. In any event, embodiments of the invention include twodifferent blue emitters in a single device, however the difference inblue is measured.

Different types of devices may be used in different lightingapplications. For example, a white lighting panel 700, such as shown inFIG. 24, may include a plurality of similar white lighting devices 710(in this case white light emitting strips). On the other hand, as shownin FIG. 23, a substantially blue emitter may be used together with, forexample, a red emitter and a green emitter to form pixels of amulti-color display 600. “Red” and “green” phosphorescent devices havinglifetimes and efficiencies suitable for use in a commercial display arewell known and readily achievable, including devices that emit lightsufficiently close to the various industry standard reds and greens foruse in a display. Examples of such devices are provided in M. S. Weaver,V. Adamovich, B. D'Andrade, B. Ma, R. Kwong, and J. J. Brown,Proceedings of the International Display Manufacturing Conference, pp.328-331 (2007); see also B. D'Andrade. M. S. Weaver, P. B. MacKenzie, H.Yamamoto, J. J. Brown, N. C. Giebink, S. R. Forrest and M. E. Thompson.Society for Information Display Digest of Technical Papers 34, 2, pp.712-715 (2008).

Other combinations are also possible, and will be appreciated by thoseof skill in the art. For example, any number of different colorcombination sub-pixels may be included in the pixel of a multi-colordisplay such as shown in FIG. 23. Additionally, in certaincircumstances, it may be advantageous to include both a substantiallyblue emitting device as described herein with a white emitting device,and/or any number of other color emitting devices.

Various types of OLEDs may be used to implement various configurations,including transparent OLEDs and flexible OLEDs.

A single pixel may incorporate three or more sub-pixels such as thosedisclosed herein, possibly with more than three discrete colors. Systemsincluding the described lighting devices may include mostly blue lightemitting devices, non-blue emitting devices, white light emittingdevices, and combinations thereof.

It is understood that the various embodiments described herein are byway of example only, and am not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

We claim:
 1. A method of fabricating a device having at least laterallypatterned first and second sub-devices, the method comprising:depositing via organic vapor jet printing (OVJP) a first organic layerof the first sub-device and a first organic layer of the secondsub-device; wherein the first organic layer of the first sub-device andthe first organic layer of the second sub-device have differentthicknesses; wherein the first organic layer of the first sub-device andthe first organic layer of the second sub-device are both the same typeof layer, and wherein the type of layer is selected from an ETL, an HTL,an HIL, a spacer, and a capping layer.